Vulcanizable compositions of an olefin polymer or copolymer and vulcanized articles obtained therefrom

ABSTRACT

VULCANIZABLE COMPOSITION OF ELASTOMERIC POLYMER, REINFORCING FILLER, FREE-RADICAL ACDEPTOR AND ORGANCI PEROXYETHER FREE-RADICAL GENERATOR WHEREIN CARBON ATOM BOUND TO BOTH ETHER AND PEROXY RADICAL IS SUBSTITUTED WITH MEMBER SELECTED FROM ALKYL, CYCLOALKYL AND ARYL RADICALS AND CONTAINS NO HYDROGEN SUBSTITUENT, AND VULCANIZED ARTICLE OBTAINED THEREFROM.

United States Patent US. Cl. 260-41 11 Claims ABSTRACT OF THE DISCLOSURE Vulcanizable composition of elastomeric polymer, rein forcing filler, free-radical acceptor and organic peroxyether free-radical generator wherein carbon atom bound to both ether and peroxy radical is substituted with member selected from alkyl, cycloalkyl and aryl radicals and contains no hydrogen substituent, and vulcanized article obtained therefrom.

CROSS REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Ser. No. 492,860, filed Oct. 4, 1965, now abandoned which is in turn a continuation-in-part of application Ser. No. 483,843, filed Aug. 30, 1965, now abandoned.

BACKGROUND OF THE INVENTION (1) Field of the invention The present invention relates to vulcanizable compositions comprising an elastomeric polymer, a reinforcing filler, a free-radical generator that is an organic peroxide having certain specified characteristics, and a free-radical acceptor. The invention also relates to the vulcanized articles obtained therefrom.

(2) Description of the prior art The use of organic percompounds together with particular free-radical acceptors as cross-linking agents for olefin polymers and for copolymers of ethylene with higher alphaolefins is known. More particularly, there has previously been described the use of monoperoxides such as dicumylperoxide and tert. butyl cumyl peroxide and of diperoxides such as 2,5 dimethyl 2,5 di(tert.butylperoxy) hexane, alpha alpha bis(tert.butylperoxy)- diisopropylbenzene, 2,5 dimethyl 2,5 di(tert.butylperoxy)hexyne-3, etc.

These percompounds have relatively low decomposition rates, resulting in vulcanization times considerably higher than those times associated with traditionally known unsaturated elastomers vulcanized with sulfur and accelerators.

It has not been possible to obtain a higher vulcanization rate with elastomers charged with carbon black using these alkyl or arylalkyl peroxides, unless the vulcanization temperature is increased.

Peroxides are also known which have a lower period of semi-decomposition and therefore a higher vulcanization rate than those described above, e.g., certain diaroylperoxides and tert.alkylperesters, such as dibenzoyl peroxide and tert.butyl perbenzoate.

However, these peroxides are somewhat disadvantageous in that they are sensitive to the reinforcing fillers of carbon black. Such fillers significantly reduce or even destroy the vulcanizing activity of such peroxides. Hence these peroxides have only a very limited practical use in 3,575,920 Patented Apr. 20, 1971 ICC the peroxidic vulcanization of natural or synthetic elastomeric materials.

In a preceding patent application, Ser. No. 343,950 filed on Feb. 11, 1964, peroxides of a new type have been described, namely, perketals and peracetals, such peroxides being characterized by a high decomposition rate accompanied by little or no sensitivity to the negative influence of reinforcing fillers particularly fillers of carbon black. These peroxides, however, produce vulcanizates having a lessened resistance to ageing.

An object of the present invention is a vulcanizable composition of a saturated or unsaturated elastomer and containing a reinforcing filler and an organic peroxide, which composition does not suffer from the disadvantages encountered when using prior art peroxidic agents.

SUMMARY OF THE INVENTION The vulcanizable compositions of the present invention comprise (1) an elastomeric polymer, namely, either a saturated amorphous copolymer of ethylene with a higher alpha-olefin, or a terpolymer of ethylene with an alphaolefin and a cyclic or acyclic polyene having non-conjugated double bonds, such terpolymer having a low degree of residual unsaturation, (2) a reinforcing filler, (3) a free-radical acceptor, and (4) a free-radical generator, namely, a peroxyether represented by the formula R1 R3o( o-oR4 or by the formula in which:

R is an unsubstituted alkyl or cycloalkyl radical containing up to 10 carbon atoms or an unsubstituted or alkyl substituted aryl radical containing up to 10 carbon atoms;

R is an unsubstituted alkyl or cycloalkyl radical containing up to 10 carbon atoms or an unsubstituted or alkyl substituted aryl radical containing up to 10 carbon atoms;

and R and R taken together with the central carbon atom, can form a cycloaliphatic ring;

R is an unsubstituted alkyl or an unsubstituted or alkyl substituted cycloalkyl, aryl, or arylalkyl radical containing up to 10 carbon atoms;

R; is an unsubstituted alkyl or an unsubstituted or alkyl substituted tertiary arylalkyl radical containing up to 10 carbon atoms;

or one of R and R but not both simultaneously may have the following formula A or B, respectively; either (A) R may have the formula in which:

R contains up to 10 carbon atoms and is an unsubstituted or alkyl substituted alkylene, cycloalkylene, alkenylene, alkynylene or arylene radical, and R R and R are as defined above, or (B) R; may have the formula:

in which:

R R and R are as defined above; R is an unsubstituted alkyl or an unsubstituted or alkyl substituted tertiary arylalkyl radical containing up to 10 carbon atoms;

R R R and R are each an unsubstituted alkyl or cycloalkyl radical containing up to 10 carbon atoms, or an unsubstituted or alkyl substituted aryl radical containing up to 10 carbon atoms. R and R are each an unsubstituted alkyl or an unsubstituted or alkyl substituted cycloalkyl, aryl, or arylalkyl radical containing up to 10 carbon atoms; and R and R and/or R and R may form a cycloaliphatic ring with the central carbon atom to which they are linked.

The present invention therefore includes new vulcanizable compositions comprising amorphous saturated copolymers of ethylene with an alpha-olefin such as propylene or butene-l, or slightly unsaturated terpolymers of ethylene with an alpha-olefin and a cyclic or acyclic nonconjugtaed diene, along with the aforedescribed peroxyethers, a reinforcing filler, and, if desired, antioxidants, coagents, and other additives conventionally employed in vulcanizable compositions.

A further aspect of the present invention relates to vulcanized articles obtained by heating the foregoing compositions to a temperature greater than the decomposi tion temperature of the peroxyethers contained therein, the heating being for a time suflicient to effect crosslinking.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Typical suitable peroxyethers conforming to the general formulae previously set forth include:

2-methoxy-2-tert.butyl-peroxy-propane 2-ethoxy-Z-tert.butyl-peroxxy-propane 2-isopropoxy-2-tert.butyl-peroxy-propane 2-isobutoxy-2-tert.butyl-peroxy-propane 2-ethoxy-2-tert.butyl-peroxy-propane 2-methoxy-2-(cumyl-peroxy)propane 2-ethoxy-2- (cumyl-peroxy) propane u-methoxy-a-tert.butylperoxy-ethylbenzene a-ethoxy-u-tert.butylperoXy-ethylbenzene a-isopropoxy-a-tert.butylperoxy-ethylbenzene u-methoxy-u (cumylperoxy) -ethylbenzene a-ethoxy-a (cumylperoxy) ethylbenzene a,a-dimethoxy-a,u-di (tert.butylperoxy) -p-diethylbenzene u,a'-dimethoxy-a,a'-di(tert.butylperoxyl) -m-diethylbenzene a,a'-diethoxy-a,ot'-di (tert.butylperoxy) -m-diethylbenzene a,a'-diethoxy-a,u'-di (tertbutylperoxy) -p-diethylbenzene a,a'-diethoxy-u,ot'-di(cumylperoxy) -m-diethylbenzene a,ot'-dimethoxy-ot,m'-di (cumylperoxy) -p-diethylbenzene ,a'-dimethoxy-u, x-di(cumylperoxy) -m-diethylbenzene c -diethoxy-w,a-di(cumylperoxy) -p-diethylbenzene 2,2-dimethoxy-diisopropylperoxide l,l-dimethoxy-1,1'-diphenyl-diethylperoxide 2,5 -di [di( 2,2-dim ethoxy isopropylperoxy] -2,5-

dimethylhexyne-3 2,2'-diethoxy-diisopropylperoxide tx-tertbutylperoxychromane 1,4-endoperoxy-l ,4-dimethoxy-cyclohexane 1,4-diisopropylbenzene-ot,a'-bis (2-ethoxy-isopropylperoxide 1, 3-diisopropylb enzene-u,u-bis (2-ethoxy-isopropylperoxide) 2-tert.butoxy-2-tert.butylperoxy-propane l-phenyl- 1 (0:,0: -dimethy1) benzylperoxy- 1 -tert.butoxyethane I-phenyl-1-tert.butylperoxy-1-tert.butoxy-ethane di- 2,2-di-tert.butoxy) isopropylperoxide l,4-di(a-tert.butoxy-u-tert.butylperoxy-ethyl)benzene The advantage offered by the aforementioned class of peroxyethers in the vulcanization of olefin polymers or copolymers, particularly ethylene-higher alpha-olefin copolymers, is that they permit a rapid vulcanization, not hindered by the presence of carbon black. Additionally, the resistance to ageing of olefin copolymers vulcanized with our peroxyethers is greater than that of the vulcanizates obtained using other types of peroxides in general, including also aryl and aralkyl peroxides.

The above described peroxyethers can be prepared according to a new method described in copending application Ser. No. 505,761, filed Oct. 29, 1965, corresponding to Italian patent application Ser. No. 23,317/ 64, filed Oct. 30, 1964, now Italian Patent 742,088, issued Jan. 16, 1967, by reacting a hydroperoxide and an alkylvinylor l-alkenylalkylether in the presence of solid catalysts in heterogeneous phase, e.g., cation exchange resins, alumina silica gel, or carbon black.

Alternatively, these peroxyethers can be obtained by applying methods known in the art for the preparation of other peroxidic compounds, such as, e.g.,

(1) addition of organic hydroperoxides or of hydrogen peroxide to alkylvinylethers, e.g., under the conditions described in U.S. Pat. No. 2,776,319 by using the traditional homogeneous acid catalysts;

(2) transperoxidation of an acetal with an organic hydroperoxide according to the general method described by Rieche et al. (Chem. Ber. 94, 2457 (1961));

(3) reaction between an alpha-substituted ether and hydrogen peroxide or an alkylhydroperoxide according to Rieche et al. (Chem. Ber. 90, 1225 (1957));

(4) reaction between a saturated ether and a hydroperoxide, catalyzed by a transition metal salt, described by Kharasch et al. (J. Org. Chem. 24, 72-78 (1959)).

The above described peroxides, present as vulcanizing agents in the compositions of the present invention, produce vulcanizates having a high resistance to ageing and exhibiting elastic characteristics superior to those obtained using other types of peroxides that exert a rapid vulcanizing action.

The mixture containing the peroxyether can be strained, extruded, and calendered at the normal temperatures employed in the rubber industry, thereby obtaining manufactured articles which, in spite of the rapid vulcanization rate, do not reveal blisters or scorching.

The amount of the peroxyether employed in the vul canizable compositions of this invention should be from about 0.1 to 20 parts by weight, preferably between l to 10 parts by weight, per parts of polymer or copolymer. The tolerable amount of carbon black may be virtually any quantity within the limits of the physical compatibility of carbon black with the polymeric material.

For ethylene-alpha-olefin copolymers vulcanized with peroxides, the effectiveness of the vulcanization and the characteristics of the resulting vulcanizates have been found to be improved when there is also added to the mix a substance which acts as free-radical acceptor such as, e.g., sulfur, quinone type compounds, vinyl and divinyl monomers, polymers containing vinyl unsaturations, dimaleimides, furfural, and their derivatives, generally in a concentration range of from about 0.01 to 10 parts by Weight, and preferably from about 0.3 to 3 parts by weight, per 100 parts of polymer or copolymer.

In the vulcanization of olefin copolymers with the peroxyethers of the present invention, it has been observed that the addition of a metal oxide, preferably zinc oxide,

in addition to the previously specified auxiliary substances, causes a further improvement in the properties of the vulcanizates. The amount of zinc oxide may be from about 0.1 to 20 parts by weight, per 100 parts by weight of polymer or copolymer.

The mixes of polymers or copolymers containing the peroxyethers, possibly reinforcing fillers, auxiliary substances, plasticizers and antioxidants known in the art, are prepared with the equipment conventionally used for mechanical mixing in the rubber industry.

The peroxyethers of the present invention are particularly well suited for the vulcanization of copolymers of ethylene with propylene and/ or butene-l, which copolymers have an ethylene content of from about 20 to 80 mole percent and a molecular weight of from about 50,000 to 800,000 corresponding to a Mooney viscosity ML (1+4) at 100 C. of from about 20 to 80. A preferred molecular weight range is from about 80,000 to 500,000.

The peroxyethers are equally well suited for the vulcanization of copolymers having a low degree of residual unsaturation, more particularly, terpolymers of ethylene with a higher alpha-olefin and a third monomer, namely a cyclic or acyclic polyene having non-conjugated double bonds, such as, e.g., terpolymers of ethylene with propylene or butene-l and cyclooctadiene-1,5; cyclooctadiene- 1,4; cyclododecadiene-1,6; cyclododecadiene-1,7; cyclododecatriene-1,5,9; cycloheptadiene-1,4; cyclohexadiene- 1,4; norbornadiene; methylnorbornene; Z-methylpentadiene-1,4; hexadiene-1,5; 6-methyl-4,7,8,9-tetrahydroindene; 5,6-dimethyl-4,7,8,9-tetrahydroindene or dicyclopentadiene, characterized by the presence of from about 0.05 to 1 double bond per 100 carbon atoms, by an ethylene content from 20 to 80 mole percent, and by the same molecular weight range as set forth above for saturated olefin copolymers.

The vulcanization may be carried out in a press, in a molten salt bath, in a fluidized solid bed, or in molds in a direct steam autoclave.

Suitable reinforcing fillers are the carbon black fillers of the various types and the mineral fillers.

The temperature at which the vulcanization is carried out is generally from about 110 to 230 C., and preferably is from about 140 to 180 C.

The following examples will further illustrate the invention. All parts are by weight unless otherwise stated.

EXAMPLE 1 2-tert.butylperoxy-2-tert.butoxy-propane was prepared according to the general method described by Kharasch and Fono (J. Org. Chem. 24, 72-78 (1959)) from tert.- butyl-isopropyl ether and tertbutyl-hydroperoxide according to the equation:

tert.BuOCH (CH +2 tert.BuO OH tert.BuOC (CH O Otert.Bu +tert.BuOH+H O 36 g. of tert.butyl hydroperoxide were added to 116 g. of tert.butyl-isopropylether in the presence of 2.5 g. of anhydrous cobalt acetate as the catalyst.

The reaction was carried out at 40 C. under nitrogen for 2 hours. The mixture was then cooled and filtered. The filtrate was washed first with water and then three times with a NaOH solution (to remove the excess of hydroperoxide). The organic layer was dried on Na SO and the excess tert.butyl isopropylether was distilled off under a low vacuum.

The residue was then rectified in an analytical column under a high vacuum, thus obtaining a fraction boiling at 3840 C. under 1 mm. Hg and having the following characteristics:

The product thus obtained was used for vulcanizing a mix having the following composition: I

Parts by weight Ethylene-propylene copolymer (55 mole percent of propylene; ML (1+4) at C.=35) 100 HAF carbon black 50 Sulfur 0.32 Zine oxide 3 2-tert.butylperoxy-2-tert.butoxy-propane 4 After vulcanization at 165 C. for 11 minutes in a press, a vulcanizate having the following characteristics was obtained:

Tensile strength, kg./cm. 168

Elongation at break, percent 500 Modulus at 300%, kg./cm. 83

Permanent set, percent 11.5

EXAMPLE 2 propylene; ML (1+4) at 100 C.=35) 100 HAF carbon black 5 0 Sulfur 0.32

Peroxide See below.

The following values (minutes) were determined in a vulcanometer at 165 C. and C., respectively:

vulcanization time, minutes at at Peroxide (type and amount) C. 150 C.

Z-tert.butyl-peroxy-2-tert.butoxy-propane;

4 parts by weight 11 45 Dicumylperoxide; 2.7 parts by weight 29 102 2,2-di(4-4-(tert.butylperoxy)cyclobexyl)propane; 3 parts by weight 6 15 2,2,5,5-tetra(tert.butylperoxy)hexane; 2.43

parts by weight 11 38 EXAMPLE 3 A mix was prepared of ethylene-propylene copolymer, containing 2-ethoxy-2-tert.butylperoxypropane and having the following composition:

Parts by weight Ethylene-propylene copolymer (55 mole percent of ethylene; ML (1+4) at 100 C.=35) 100 HAP carbon black 50 Zinc oxide 3 Sulfur 0.32 Peroxide (97%) 5.28

The mix was vulcanized at 150 C. for 30 minutes to give a vulcanizate having the following mechanical characteristics:

Tensile strength (kg/cm?) 169 Elongation at break (percent) 405 Modulus at 200% (kg/cm?) 60 Modulus at 300% (kg/cm?) 114 Permanent set (percent) 8.5

EXAMPLE 4 A mix of ethylene-propylene copolymer containing H. Stemmer, Katutschuk un d Gummi, 14 (5), WT 146 (1961).

alpha methoxy-alpha-tert.butylperoxy-ethyl-benzene and having -the following composition was prepared:

Parts by weight Ethylene-propylene copolymer (as in Example 3) 100 8 EXAMPLE 6 A mix of ethylene-propylene copolymer containing alpha-methoxy-alpha-cumyl peroxy-ethylbenzene and having the following composition was prepared:

HAF carbon black 50 Sulfur 0.32 Parts by weight Zinc oxide 3 Ethylene-propylene copolymer (as in Example 3) 100 Peroxide (99%) 6.48 HAF carbon black 50 With this mix, progressive vulcanization tests were oxlde 0 carried out at temperatures of 165 C. for successively i 0 increasing times. The vulcanizates had the following chareroxl a) f acteristics as reported in Tables A and B below: Vulcamzauon: at 140 for 45 mmutes" 7 TABLE A The vulcanizate obtained showed the following mechan- [Temperamm ical characteristics:

Time in minutes 2 4 6 8 10 T 1 h (k 175 ens1e strengt g. cm. T 11 st; m1; 160 199 192 189 181 190 f rg io gigri ag/ 36 11: 63g 42g 423 4g; 32g 4 5 g i g 0 c, 8 o u us at 0 g. cm.) M d 1 t300 ,k 57 103 119 125 131 134 Pgniia ii e tsetf fierift i n 15 11 7.5 6.5 7.5 6.5 20 Modulus at 103 ISO hardness 57 61 62.5 62 62 62.5 Permanent set (percent) 8 ISO hardness 61 As can be seen from Table A above, complete vulcanization was reached after 10 minutes at 165 C. EXAMPLE 7 The highest degree of vulcanization was reached after minutes at 150 C. (See Table B below.) A mix of ethylene-propylene copolymer, containing TABLE B lTemperature: 150 0.]

Time in minutes 4 8 12 16 20 24 28 30 Tensile strength, kgJcmfi 31 79 144 161 171 170 174 170 180 Elongation at break, percent i. 870 80 650 600 525 455 435 420 415 Modulus at2(K)%, kg./cm. 10 14 24 24 41 45 52 55 55 Modulus at300%,kg./cm. 12 26 4s 62 75 31 93 105 10s Permanent set, percent 50 26 16 13 10 9 7 7 Iso hardness 48 53 5s 60.5 62 62 64 63 EXAMPLE 5 45 alpha isobutoxy-alpha-tert.butylperoxy-ethyl-benzene and The resistance to ageing in an air oven of the vulcanhavmg the follo'wmg formulation was prepared: izate obtained by using alpha-methoxy-alpha-tert.butyl- Parts by weight peroxy-ethyl-benzene was measured and compared with Ethylene-propylene copolymer (as in Example 3) 100 that obtained using cumyl peroxide. HAP carbon black 50 Mixes having the following composition were prepared: 50 Zinc Oxide 3 Sulfur 0.32 Parts by Peroxide (95%) 5.32

Vulcanization: at 150 C. for 9 minutes. A B 55 The vulcanizates showed the following mechanical Ethyl-propylene copolymer (as in Example 3) 1 characteristics: HAF carbon black 50 Polymerized1,2-dihydro-2,2,4trimethy1quinoline 0,5 Tenslle Stfe11gth g/ 175 g g El llga lon at break (percent) 440 Al h -methtiiiflafphe iifiiafiiiipiiir iffil 'fifiifl 'MOdUlllS at 0% (kg-/ :m. 56 'j 5555; 55:- Modulus at g 110 Permanent set (percent) 7.5 IS The specnnens thereof, vulcanized under the same con- 0 hardness 6o ditions at 165 C. for 30 minutes, were aged in an oven EXAMPLE 8 at a temperature of 150 C. Periodic measurements of their tensile strengths gave the following values:

Tensile strength (kg lcmfl) Time, days was prepared.

The mix had the following composition: The vulcanizate obtained showed the following mechan- Parts by Weight ical characteristics: Et yl n -pr py copolymer in Example 100 Tensile strength (kg/cm?) 168 carbon black 50 Elongation at break (percent) 450 Z1116 OXlde 3 5 Modulus at 200% (kg/cm?) 52 Sulfur Modulus at 300% (kg/cm?) 103 PerOXldF (9 Permanent set (percent) 8.5 Vulcan1zat1on: at 150 C. for 25 minutes. 150 hardness The yulcanizate obtained showed the following char- 10 EXAMPLE 11 acterlsticsz Tgnsile strensth (kg/emu) 173 A mlX hy -p py po ym Containing Elongation break (percent) 416 p a p n h0Xy-a1pha, lp a 1-tert-b yl-per- Modulus at 200% (kg/cm?) 61 0XIV-P-lltthyl'lmzene Modulus at 300% (kg./cm. 118 10 Permanent set (percent) 7.5 ISO hardness 61 EXAMPLE 9 A mix of ethylene-propylene copolymer containing 2- butyl l tert. butyl-peroxy 2 isopropoxy-propane and having L the following formulatlon was prepared:

Parts by weight O CH3 CH3 Ethylene-propylene copolymer (as in Example 3) 100 HAP carbon black 50 Zinc oxide 3 Sulfur 0.32 Peroxide (95% 5 and having the following composition, was prepared: Vulcanization: at 165 C. for 15 minutes. Parts by Wight The vulcanizate showed the following mechanical Ethylene-propylene copolymer (as in Example 3) 100 characteristics: HAF carbon black 50 Tensile strength (kg/cm?) 171 Oxlde g Elongation at break (percent) 430 u 2 Peroxide (85%) 6.4 Modulus at 200% (kg/Cm 56 vulcanization" at 150 C for 25 minutes Modulus at 300% (kg/cm?) 103 Permanent Set (P 8 The vulcanizate showed the following mechanical ISO hardness 52 characteristics:

40 EXAMPLE 1O Tensile strength (kg/cm?) 168 A mix of ethylene-propylene copolymer containing 1,4- Elongation at break (percent) 410 di[2,2'-di(ethoxy isopropylperoxy)isopropyl]benzene, Modulus at 200% (kg/cm?) 56 CH3 CH3 CH3 CH3 Modulus at 300% (kg/cm?) 107 I I 1 Permanent set (percent) 8 f$ f rso hardness 61 CH3 CH3 CH3 CH3 EXAMPLE 12 and having the followlng formulat1on, was prepared:

Parts y Weight ThlS example 1 lustrates the superior results obtalned particularly as regards higher modulus and lower perg g g i copolymer (as m Examp 1e 3 2g manent set, which are obtained when employing a per- Zin ig ac 3 oxide of the present invention as compared with a similar g s 0 32 peroxide wherein R is hydrogen. The compositions vulgg; 5 canized, the vulcanizing conditions and the properties a) of the resulting vulcanizates are set forth in Table 1 vulcanization: at 165 C. for 10 minutes. below.

TABLE 1 Ethylene-propylene by 11101) copolymer (ML-35) 100 100 100 100 HAF carbon black Zinc oxide S ur l-tert. butyLperoxy-l-sec.-butoxy-ethane, parts by weight (m01s) orTert.butyl-peroxy-os-seobutoxy-ethy1benzene, parts by weight (mols 1 tert.butyl-peroxy-1-tert.butoxy-ethane, parts by weight (mols) 2. 1 (0.0113) a-Tert.butyl-peroxy-a-tert.butoxy-ethyl-benzene, parts by weight (mols) 3 (0.0113) vulcanization conditions, minutesl C 30/165 30/165 30/165 30/165 30/165 Tensile strength, kg./cm. 150 178 93 211 164 Elongation at break, percent 585 440 825 400 490 Modulus at 200% elongation, kg./cm. 25 62 25 75 46 Modulus at 300% elongation, kgilcmfl 52 34 80 Permanent set at 200% elongation, percent 15 10 28.0 10 11. 5 ISO hardness, percent 57 56. 5 57 71. 5 56 It will be seen that far superior results are obtained in runs 2, 4 and 5, wherein peroxides of the present invention are employed. Particularly noteworthy is the fact that superior results are obtained in run 5 even though only slightly more than half the molar amount of perox- 12 The mixes were vulcanized at 165 C. for 30 minutes and the specimens prepared therefrom were placed in an oven at a temperature of 150 C. for the ageing tests. The variation of the tensile strength of the vulcanizates was measured periodically. The results are set forth 5 rde is employed as compared with the amount of peroxide in Table 4. employed in run 1. TABLE 4 EXAMPLE 13 Percent residual tensile strength In order to compare vulcanization times achieved with 12 13 14 15 the peroxides of the present invention as compared with 100 100 100 100 those wherein R is hydrogen, several vulcanizable mixg 32 gg tures were prepared, using an ethylene-propylene copoly- 94 9g 77 50 mer (60% by mols of propylene, ML (1+4) at 100 84 92.5 57 23 12. 5 s1 15 (1:35). The vulcanization times were tested by the 5 515 66 method described by H. D. Stemmer, Keatschuk and fl 14 WI 146 (1961)- The miXtureS had the From the percent residual tensile strength set forth in following composltlonl 100 Parts y Welght P Y E Table 4, it is clear that vulcanizates 12 and 13, obtained 50 parts of HAF carbon black, 0.32 part by weight of sulusing a curing agent a peroxyether of the present invenfur and the same molar amount of one of the peroxides, tion, exhibit a remarkably higher resistance to ageing than as set forth in Table 2. vulcanizates 14 and 15, which were cured with a peroxy- The vulcanlzatlon of the mixes was then carried out ether wherein R is hydrogen. at 150 C. and, respectively, at 165 C. and the time EXAMPLE 15 thereof in minutes was determined in a curometer, as reported in Table 2, 25 The resistance to ageing of various vulcanizates was measured in order to compare the influence of the type of peroxide used. TABLE 2 The following mixes were prepared:

vulcanization time, minutes Mix containing the following peroxide at 150 C. at 165 C. A B C D 6- l-tert.butylperoxydetmxy-ethane, 39 17 Ethilfne'pmpylene copolymer (as in Example 100 100 100 m0 7- Al pl i a szil fb ii tgg ziy alphaethoxy- 24 9 i 2 2 4 l u 50 50 50 50 ethylbenzene, 5.6 parts by weight f g y I 1 r e y qum 0 5 o 5 0 0 8- 1firgebuiglperoxy-llseebutoxy-ethane, 49 I5 sulfur 4 4 '2 '2 t par yweig T W 9 Alpha-tart.bntylrggoxy-zglpgia-see.lfitpxyl9 8 ggffjg 6 "31;

B Y 81128118, par S y WBlg I u 10.- l-teat.buty?eroxy-i'ternbutoxy-ethane, 39 12 r ggi ls(tQILblltyl-peruxfimyclohexyh- 3 7 7 parts yweig 11 Allgha439mbutylperoxyalphgbutoxy 31 6 2,2,5,5-tetra(tert-butylperoxwhexane 8 ethylbenzene, 3.0 parts by weight 40 1 The different amounts by weight used in the above mixes were such as to impart to the vulcanizates obtained therefrom the same degree of crogslinking, From these mixes some specimens vulcanized at 165 C. for 30 minutes were prepared. They were placed inan vn tatmr It 1s clear that mixes 7, 9 and 11, containing the peroxand z i f i f 2 2 C i agemg ides of the present invention, are vulcanized at consider- 11 cu ensl e 8 was measure ably shorter vulcanizing times than mixes 6, 7 and 10, perm containing peroxides wherein R1 is hydrogen. The four vulcamzates give the following values:

EXAMPLE 14 T Percent residual tensile strength uno,

The resistance to ageing of various vulcanizates was days A B C D measured in order to compare the influence of the type 0 100 100 100 100 of peroxide used. 2 93 37 87 The following mixes were prepared as set forth 1n Table 6 00 81 27 1g 3, in which the amounts used are listed in parts by weight 55 5 2g 13 15 (and, for the peroxides, the amount in mols is also in- 12:11:11: 50 as IIIIIIIIIIIIII dicated in brackets).

TABLE 3 Parts by weight (mols) Component 12 13 14 15 Ethylene-propylene copolymer (607 by mols of propylene) ML 1+4) at 100 0.=a5 .f 100 100 100 100 HAF carbon black 50 5O 50 ZnO 3 3 3 a Polymerized 1,2-dihydro-2,2, 0. 5 0. 5 0. 5 0. 5 s fur 0.4 0.4 0.4 0.4 Alpha-methoxy-nlpha-tert.butylperoxy-ethylbenzene 7 1 (0. 0312) Alpha-isobutoxy-alpha-tert.butylperoxy-ethylbenzene I (0 06.52;:

. 2 l-tert. butylperoxp-l-tert. butoxy-e h n 7. 0

(0. 0368) 1-sec.butoxy-1-tert.butylperoxy-ethane 7. 5 1 (0. 0395) 1 The different amounts by mols used in the above mixes were such as to impart to the vulcanizates obtained therefrom the same degree 01 cross-linking.

13 EXAMPLE 16 In a common roll mixer a mix having the following composition was prepared:

Parts by weight Ethylene/propylene (60 mole percent) /6-methyl- 4,7,8,9-tetrahydroindene (1.02% mol) terpolymer; ML (1+4) 100 C.=40 100 HAF carbon black 50 Zinc oxide 3 Sulfur 0.35 Z-methoxy-Z-tert.butyl-peroxy-propane 4.6

1 This amount refers to propylene.

'From the mix a lamina vulcanized in a press at 165 C.

for 12 minutes was prepared which had the following characteristics:

prepared:

Parts by weight Ethylene-propylene copolymer (as in Example 1) 100 HAF carbon black 50 Zinc oxide 3 Sulfur 0.32

u-Methoxy-a-cumylperoxy-ethylbenzene 7.0

From this mix a lamina vulcanized in a press at 165 C. for 11 minutes was prepared, on which the following Variations can, of course, be made without departing from the spirit and scope of the invention.

Having thus described our invention, what We desire to secure by Letters Patent and hereby claim is.

1. Vulcanizable compositions containing 1) an elastomeric polymer selected from the group consisting of a saturated amorphous copolymer of ethylene with a higher alpha-olefin and a terpolymer of ethylene with a higher alpha-olefin and a cyclic or acyclic polylene having non-conjugated double bonds, said terpolymer having low residual unsaturation, (2) a carbon black reinforcing filler, (3) a free radical acceptor and (4) a free radical generating agent selected from the group consisting of peroxyethers of the formulae:

and

wherein R is an unsubstituted alkyl or cycloalkyl radical containing up to 10 carbon atoms or an unsubstituted or alkyl substituted aryl radical containing up to 10 carbon atoms; R is an unsubstituted alkyl or cycloalkyl radical containing up to 10 carbon atoms or an unsubstituted or alkyl substituted aryl radical containing up to 10 carbon atoms; and R and R taken together with the central carbon atom, can form a cycloaliphatic ring; R is an unsubstituted alky or an unsubstituted or alkyl sub stituted cycloalkyl, aryl, or arylalkyl radical containing up to 10 carbon atoms; R; is an unsubstituted alkyl or an unsubstituted or alkyl substituted tertiary arylalkyl radical containing up to 10 carbon atoms; or one of R and R but not both simultaneously, may have the following formula A or B, respectively; either (A) R may have the formula:

wherein R contains up to 10 carbon atoms and is an unsubstituted or alkyl substituted alkylene, cycoalkylene, alkenylene, alkinylene or arylene radical, and R R and R are as defined above, or (B) R may have the formula:

wherein R and R and R are as defined above; R is an unsubstituted alkyl or an unsubstituted or alkyl substituted tertiary arylalkyl radical containing up to 10 carbon atoms; R R R and R are each an unsubstituted alkyl or cycloalkyl radical containing up to 10 carbon atoms, or an unsubstituted or alkyl substituted aryl radical containing up to 10 carbon atoms; R and R are each an unsubstituted alkyl or an unsubstituted or alkyl substituted cycloalkyl, aryl, or arylalkyl radical containing up to 10 carbon atoms; and R and R and/or R R may form a cycloaliphatic ring with the central carbon atom to which they are linked.

2. The composition of claim 1 wherein at least one of thfi radicals R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 contains an alkyl substituent.

3. The vulcanizable composition of claim 1 wherein the peroxyether is present in an amount of from about 0.1 to 20 parts by weight per 100 parts of elastomeric polymer.

4. The composition of claim 3 wherein the amount of peroxyether is from about 1 to 10 parts by weight.

5. The vulcanizable composition of claim 1 wherein the free-radical acceptor is sulfur, a quinone compound, a vinyl or divinyl monomer, an alkyl or polyalkyl monomer, a polymer containing vinyl unsaturation, a dimaleimide, furfural, or a derivative of any of the foregoing, and is present in an amount of from about 0.1 to 10 weight percent based on the Weight of said polymer.

6. The composition of claim 5 wherein the amount of said free-radical acceptor is from about 0.3 to 3 weight percent.

7. The vulcanizable composition of claim 1 which further contains a metal oxide in an amount of from about 0.1 to 10 weight percent, based on the weight of said polymer.

8. The vulcanizable composition of claim 1 wherein said elastomeric polymer is a copolymer of ethylene with an alpha-olefin, said copolymer being a saturated amorphous copolymer of ethylene with propylene or butene-l and having an ethylene content of from about 20 to mole percent and a Mooney viscosity, ML (1+4) at C., of from about 20 to 80, corresponding to a molecular weight from about 50,000 to 800,000.

9. The vulcanizable composition of claim 1 wherein said elastomeric polymer is a terpolymer said terpolymer being selected from the group consisting of terpolymers of ethylene with propylene and a third monomer from the group consisting of cyclooctadiene-1,5, cyclooctadiene- 1,4, cyclododecadiene-1,6, cyclododecadiene-1,7, cyclododecatriene-1,5,9, cycloheptadiene-1,4, cyclohexadiene- 1,4, norbornadiene, methylnorbornene, Z-methylpentadicue-1,4, hexadiene-LS, 6-methyl-4,7,8,9-tetrahydroindene, 5,6-dimethyl-4,7,8,9-tetrahydroindene and dicyclopentadiene, said terpolymer containing from about 0.05 to 1 double bond per 100 carbon atoms, having a molecular Weight of from about 50,000 to 800,000 and an ethylene content of from about 20 to 80 mole percent.

10. The composition of claim 9 wherein the molecular Weight of said terpolyrner is from about 80,000 to 500,000. 10

11. The composition of claim 1 in vulcanized form.

References Cited UNITED STATES PATENTS 2/1958 Bankert et al. 26088.1 8/1966 Scott 260-88.1

U.S. Cl. X.R.

UNITED STATES PATENT OFFICE l (56 CERTIFICATE OF CORRECTION Patent No. 3,575,920 Dated April 20, 1971 Inventofls) GIULIANO BALLINI and CARLO BUJTAR It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, first structural formula, that portion of the formula reading -('JO-R should read R2 II Column 3, line 29: "conjugtaed" should read conjugated line 45: "peroxxy" should read peroxy line 58: "(tel butylperoxyl)-" should read (tert.butylperoxy)- Colur 4, line 26: After "alumina" insert a comma (O Column 7, line 56: "Ethyl-propylene" should read Ethylene-propylene Column 10, line 49: After "obtained" insert a coma Coluums 9 and 10, Table I, second line under heading "5":

should read 5O Column 11, T Containing, etc. first line: under same heading: "7,0" should read 7.0 and 12, Table 3, under heading "Component", should read butylperoxy Column 13, Claim 1, line 52: "polylene" should read polyene 2: "alky" should read alkyl line 28: "R and R R should read R R and R line 38: "R R read R3 and R Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer ROBERT GOTTSOHALK Commissioner of Patents able 2, under heading "Mi: "etroxy" should read etho: Columns 11 line 9, "butylpe:

Column 14, Claim 1, 1: an Sh 

